according to current laws in many nations yes it is theft to DL copyrighted files via p2p.
i choose to view it as property collectivisation, which i see as a political act, since i don't monopolise possession of the files i DL their not exactly 'mine' they could easily be 'yours'.
this is however the wrong place to try to take an ethical moral stand, this board is dedicated to p2p methods and the curtailing of all methods which may hinder file sharing.